374 research outputs found
ParFORM: recent development
We report on the status of our project of parallelization of the symbolic
manipulation program FORM. We have now parallel versions of FORM running on
Cluster- or SMP-architectures. These versions can be used to run arbitrary FORM
programs in parallel.Comment: 5 pages, 6 Encapsulated postscript figures, LaTeX2e, uses espcrc2.sty
(included). Talk given at ACAT0
Limits on Lorentz Violation from the Highest Energy Cosmic Rays
We place several new limits on Lorentz violating effects, which can modify
particles' dispersion relations, by considering the highest energy cosmic rays
observed. Since these are hadrons, this involves considering the partonic
content of such cosmic rays. We get a number of bounds on differences in
maximum propagation speeds, which are typically bounded at the 10^{-21} level,
and on momentum dependent dispersion corrections of the form v = 1 +-
p^2/Lambda^2, which typically bound Lambda > 10^{21} GeV, well above the Planck
scale. For (CPT violating) dispersion correction of the form v = 1 + p/Lambda,
the bounds are up to 15 orders of magnitude beyond the Planck scale.Comment: 24 pages, no figures. Added references, very slight changes. Version
published in Physical Review
Higgs Boson Production at Hadron Colliders
I report on a calculation of the inclusive Higgs boson production cross
section at hadron colliders at next-to-next-to-leading order in QCD. The result
is computed as an expansion about the threshold region. By continuing the
expansion to very high order, we map the result onto basis functions and obtain
the result in closed analytic form.Comment: 3 pages, 2 figures, uses espcrc2.sty. Talk presented at XXXIst
International Conference on High Energy Physics, Amsterdam, The Netherlands,
24-31 July, 200
alpha_s^3 conversion relation betweeen MS-bar and Euclidean quark masses
We report on the analytical calculation of NNNLO (of order alpha_s^3)
conversion factor between the MS-bar quark mass and the one defined in the
so-called Regularization Invariant scheme. The NNNLO contribution in the
conversion factor turns out to be relatively large and comparable to the known
NNLO term.Comment: 4 pages, Latex, uses espcrc2.sty. The paper is also available via
anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ttp99/ttp99-39/ or via
www at http://www-ttp.physik.uni-karlsruhe.de/Preprints
Next-to-next-to-leading logarithmic threshold resummation for deep-inelastic scattering and the Drell-Yan process
The soft-gluon resummation exponents G^N in moment space are investigated for
the quark coefficient functions in deep-inelastic structure functions and the
quark-antiquark contribution to the Drell-Yan cross section dsigma/dM.
Employing results from two- and three-loop calculations we obtain the
next-to-next-to-leading logarithmic terms alpha_s (alpha_s ln N)^n of G^N to
all orders in the strong coupling constant alpha_s. These new contributions
facilitate a reliable assessment of the numerical effect and the stability of
the large-N expansion.Comment: 9 pages, LaTeX, 2 eps-figure
Parton distribution functions from the precise NNLO QCD fit
We report the parton distribution functions (PDFs) determined from the NNLO
QCD analysis of the world inclusive DIS data with account of the precise NNLO
QCD corrections to the evolution equations kernel. The value of strong coupling
constant \alpha_s^{NNLO}(M_Z)=0.1141(14), in fair agreement with one obtained
using the earlier approximate NNLO kernel by van Neerven-Vogt. The intermediate
bosons rates calculated in the NNLO using obtained PDFs are in agreement to the
latest Run II results.Comment: 8 pages, LATEX, 2 figures (EPS
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